In my prior U.S. Pat. No. 3,496,636 granted Feb. 24, 1970, entitled "KEY CUTTING MACHINE WITH PRESELECTED DEPTH GAUGING" and in my prior U.S. Pat. No. 3,633,451 granted Jan. 11, 1972, entitled "KEY CUTTING MACHINE WITH COORDINATED POSITIONING AND CUTTING MOVEMENTS", there are disclosed improved forms of code cutters which utilize a "readout" form of preselected depth gauging by means of which the entire code sequence of cuts for the key blank can be preset on the machine before any cuts are made.
With the advent of and trend toward lighter weight automobiles, the automobile manufacturers have progressively reduced the thickness of automobile doors so that the available space for the lock assembly for the doors has been considerably reduced. The lock manufacturers have accordingly found it necessary to reduce the length of the lock cartridge or mechanism. Correspondingly, the keys for these locks have been reduced in length and the customary uniform spacing between adjacent cuts on the key have also been reduced. As a consequence, the cuts on existing keys are often shallower than has been standard practice in the art, and the first cut on many keys is so close to the shoulder of the key that a cut of less than standard width has to be made, otherwise the shoulder itself would be eliminated by the cut. Inasmuch as the shoulder of the key is necessary to precisely limit the extent of insertion of the key in the lock for proper operation, any mutilation or cutting away of the shoulder of the key must be avoided. Furthermore, in making replacement keys, the shoulder serves as the reference point for the cuts to be made on the key, so it is necessary that the shoulder not be damaged during the course of the cutting operation on a replacement key.
In addition to the above-mentioned changes which have occurred in automotive locks and keys, there has also been a strong impetus toward improving the security of automotive locks and keys to prevent theft. This has resulted, for example, in double-edged keys and corresponding locks, as well as an increase in the number of tumblers or wafers with a corresponding increase in the number of cuts on the key. In the past, automotive keys ordinarily had five or six cuts. Presently, there are automotive keys that have as many as twelve cuts compressed into the same space which formerly accommodated five or six cuts.
The cutting of the original key by the automotive lock manufacturer poses no particular problem because the manufacturer can utilize specialized, high production key cutting tools and equipment for the mass production of the original keys. However, when replacement keys are required, automobile dealers and locksmiths do not have such single purpose equipment for key cutting, particularly code key cutting, and must utilize code key cutters of the type described in the foregoing patents and use interchangeable accessories to accommodate to different key cutting situations.
Thus, in the type of key cutting circumstance mentioned above, a locksmith attempting to use a code cutter to replace a lost key, would have to replace the standard cutting punch of the code cutter with a smaller punch to make the first cut on the key without damage to the shoulder of the key. After the first cut, the punch would have to be replaced again with a standard punch to finish the remaining cuts on the key. This involves considerable time and work for the locksmith.
It has also been found that with the increased number of cuts on a key balnk and with the advent of double-edge keys, a much greater degree of precision is required in making replacement keys. Heretofore, when only five or six cuts were required in an automotive replacement key, some slight inaccuracies could be tolerated without affecting the operabiity of the key in the lock. Such inaccuracies could result from normal wear on the cutting punch or other elements of the code key cutting device. Such inaccuracies also could result from a weakening of the spring linkage between the key blank support member and the operating lever of the apparatus of the type disclosed in my above-mentioned patents. Such a weakening of spring tension sometimes permits the key blank support member to be displaced slightly during the key cutting process, as the spring may no longer be sufficiently strong to retain the support member in the desired cutting depth position. Dullness of the cutting punch could also create a force vector tending to displace the support member in opposition to its spring tension. Such minor inaccuracies cumulate and compounded by increasing the number of cuts on the key, and therefore often produce a replacement key which does not operate properly.
In order to avoid the problem associated with making the first cut on the key blank with a different sized cutting punch than is used for the remainder of the cuts, some locksmiths have resorted to ordering key blanks from the manufacturer which have the first cut already provided therein. This procedure requires the locksmith to maintain a large inventory of a variety of precut, first cut key blanks of different depths and shapes in order to render prompt service to replacement key customers. Furthermore, the possibility of inaccuracies in the remaining standard cuts on the key blank still exists, even when a pre-cut key blank is used for the first cut.
The present invention is directed to overcoming both of the foregoing problems by improvements on key cutting devices of the type disclosed in the foregoing patents.